Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/158

64 chalk several inches long below the peat, during an excavation made for foundations of a chimney. This chalk may have fallen into fissures of the limestone during the denudation of the Cretaceous series, and have been washed out again at a comparatively recent period.

The quantity of gravel now left in the valley of the Aire may only represent the portion of water-rolled debris arrested in transitu to the sea, at a period when there occurred atmospheric changes of a character and importance sufficient to reduce the flow of water to its present insignificant amount.

My object in selecting the gravel-deposit of the river Aire as an illustration for examination is because that river flows over a variety of distinct strata, and yields evidence of the transport of a number of large boulders from its source to near its outfall. Then its source is in a district in which occur the celebrated caves of Kirkdale, so rich in the large Mammalia, such as Elephant, Rhinoceros, Hippopotamus, and Hyæna, and containing in the upper part of the cave-deposits human skeletons and pottery.

Although at Bingley itself no Mammalian remains have been noticed, yet at Leeds, twelve miles lower down the river, the following description of the discovery of Hippopotamus sufficiently identifies the Leeds gravel with the cave-gravel of the limestone district by means of its organic remains, and with the Bingley gravel by means of mineral character and stratigraphical position.

Mr. H. Denny, of Leeds, records the discovery, on the 3rd of April 1852, of great portions of the skeletons of two or three large specimens of Hippopotamus major at the angle formed between the river Aire and Wortley Beck, close to Holbeck Station, Leeds, at a height of 115 feet above the sea, and 20 feet above the banks of the Aire.

Mr. Denny writes, ('West Riding Geological Society Reports for 1854,' p. 325):—"The bones were discovered in a dark-blue sedimentary clay almost approaching mud, and appear from their condition to have belonged to animals which had lived and died in the immediate vicinity, and were subsequently drifted, together with fragments of trees to the bottom or lower part of a swamp, found only in this particular bed of clay, confined to one portion of the field; but the clay becomes much thicker, and reaches 10 feet in thickness as it approaches this spot, thus clearly indicating it to have been lower than the remainder of the brickfield."

Beds of clay of variable quality resting upon gravel, with occasionally large boulders, some of which contain impressions of Stigmaria and fragments of trees to the depth of 10 feet, yielded the bones of three individuals of Hippopotamus major, whose skeletons seem to have been complete when deposited. The canine tusk of one individual was 18 inches long, by 2$1⁄4$ broad. Mr. Denny observed that the vertebral column of one Hippopotamus extended in a line across the trench; the ribs appear to have been in situ; and from its position he considered that the animal had been lying on its side. Portions of the Elephas primigenius, with molar teeth, and fragments